Centralized computer systems with multiple terminals for accessing the centralized computer systems were once the dominant computer architecture. Mainframe computers were shared by multiple users wherein each user had access to a terminal system coupled to the mainframe computer.
In the late 1970s and early 1980s, personal computer systems revolutionized the computing industry by allowing each individual user to have access to their own full computer system. Each user could run their own applications and did not need to share any of the personal computer's resources with any other user.
Although personal computers have become the dominant form of computing, there has been a resurgence of the centralized computer with multiple terminals form of computing. Terminal based systems can have reduced maintenance costs since users cannot easily introduce viruses into the system or load in unauthorized program. Furthermore, modern personal computer systems have become so powerful that their substantial computing resources generally sit idle for the vast majority of the time.